Forming means for profile grinding wheels



April 1955 c. B. A. PORTER 9 14 FORMING MEANS FOR PROFILE GRINDING WHEELS Filed Sept. '7, 1951 5 Sheets-Sheet 1 ATTORNEK April 5, 1955 c. B. A. PORTER FORMING MEANS FOR PROFILE GRINDING WHEELS Filed Sept. 7, 1951 5 Sheets-Sheet 2 Arr);-

April 5, 1955 c. B. A. PORTER FORMING MEANS FOR PROFILE GRINDING WHEELS Filed Sept. 7, 1951 '5 Sheets-Sheet :s

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FORMING MEANS FOR PROFILE GRINDING WHEELS Filed Sept. 7. 1951 S Shaets-Sheet. 4

5 Sheets-Sheet 5 ORNEYS C. B. A. PORTER m v we m llffflllf F k April 5, 1955 FORMING MEANS FOR PROFILE GRINDING WHEELS Filed Sept. 7, 1951 United States Patent FORMING MEANS FOR PROFILE GRINDING WHEELS Charles Benjamin Albert Porter, Yeovil, Somerset, England, assignor to Harold Stuart Hallewell, Hillingdon Heath, England Application September 7, 1951, Serial No. 245,462

Claims priority, application Great Britain September 8, 1950 4 Claims. (Cl. 125-11) This invention relates to a pantographic wheel-dressing device adapted to be attached to a grinding machine and employed for forming on the grinding wheel thereof a profile reproduced from a template.

Such a device comprises a link parallelogram pantograph, a template follower member mounted in a bearing in one of the pantograph arms and rockable about the axis of the bearing, a dressing-tool holder mounted as a cantilever in another bearing in one of the pantograph arms and rockable about the axis of the said other bearing, and a connection supplementary to the pantograph for constraining the template follower member and the dressing-tool holder to rock in unison.

The device is intended to be used with the periphery of the grinding wheel set tangentially with respect to the rocking axis of the dressing-tool holder, the direction of rotation of the grinding wheel relatively to the cantilever dressing-tool holder being such as to tend to move the dressing-tool away from the grinding wheel periphery. However, with some recent types of grinding machines, for example, that in which the grinding wheel is mounted for both vertical movement and horizontal traversing movement, it is impossible to mount a known wheeldressing device in the required position on the machine table, since the grinding wheel mounting is bulky and the device cannot be moved sufficiently close to the grinding wheel without the vertically-extending portions of the device fouling the grinding wheel mounting.

An object of this invention is to provide a wheeldressing device which will avoid this difiiculty.

Another object is to provide a wheel-dressing device in which the dressing-tool holder is supported between spaced bearings in a rigid unitary member.

A device embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings wherein:

Figure l is a plan view on a reduced scale of the device, part of the base not being shown.

Figure 2 is a section taken on the line 2P2 in Figure 1 and drawn to a larger scale.

Figures 3A and 3B are on the larger scale and together constitute a view partly in elevation and partly in section, the section being taken on the line 33 in Figure 2.

Figure 4 shows on the larger scale a detail and is taken on the line 44 in Figure 2.

Figure 5 is a section taken on the line 5-5 in Figure 3B and drawn to the larger scale, and

Figure 6 corresponds to Figure 3B, but is a section taken on the line 6-6 in Figure 1 and drawn to the smaller scale.

The device includes a baseplate 10 to which are fixed plates 11 adapted to be engaged by the magnetic chuck of a grinding machine (not shown). A tubular bracket 12 (Figures 3A and 3B) rigid with the base carries a support 13 to which a template (not shown) can be fixed. When in position the template lies in a vertical plane parallel to the axis of the grinding wheel 14 (Figure 2); the template is located on the support by a horizontal straight edge 15 and an end stop 16.

The first long arm of the link parallelogram is constituted by a more or less horizontal H-section link 17 pivoted to a more or less vertical short link 18 about a horizontal axis 19 which is fixed relatively to the base plate 10 and is perpendicular to the plane of the template. The short link 18 constitutes one part of the second arm "ice of the link parallelogram and is pivoted about the axis 19 of a mounting 20 on the base plate. A. tubular lever 21 parallel to the short link 18 is pivoted to the free end of the long link 17 at 22 and carries a template-follower pin 23 at its upper end. A light alloy casting 24 and 24A constitutes the third, long arm of the parallelogram, this third arm being forked. The portion 24 of the casting extends parallel to the long link 17 and constitutes one prong of the fork and the portion 24A extends transversely of the link and constitutes the other prong. The prong 24, which is of inverted channel section with boxed-in ends, also serves to protect the bearings of the link parallelogram from dust, etc. The prong 24 is pivoted to the lever 21 at 25 and to the short link 18 about an axis 26. The portion of the lever 21 between the pivots 22 and 25 constitutes the fourth, short arm of the parallelogram.

The base 10 is also forked, the portion 10A carrying at its free end a mounting 20A, similar to the mounting 20. A short link 18A is pivoted to the mounting 20A about an axis 19A coaxial with the axis 19 and to the prong 24A about an axis 26A coaxial with the axis 26.

The short link 18A is the other part of the said second arm, the two links 18 and 18A together constituting this arm.

A dressing-tool holder 27 is mounted on the third arm near to the end which is pivoted to the short links 18 and 18A and for rotation about an axis 28, which is perpendicular to the plane of the template. One end of the holder 27 is secured to a shaft 29 mounted in the prong 24 and the other end is secured to a shaft 29A mounted in the prong 24A. Each of the shafts 29 and 29A is mounted in a pair of ball bearings 31 and 31A respectively, the pair 31 being held against axial movement by a pin 32. The pair 31A are capable of axial movement in their housing and, thus, small changes due to temperature variations can be accommodated in the length of the holder 27. The holder 27 is readily removable from the device by withdrawing retaining screws 33 and moving the holder radially of the axis 28, bosses 34 (see Figure 4) and 34A on the shafts 29 and 29A respectively being slidable in radial slots 35 and 35A respectively in the holder. When the holder is in position on the device it is located accurately radially of the axis 28 by means of two sets of three grub screws 36 and 36A, each set forming a three point mounting for its respective boss 34 or 34A.

The dressing tool is a diamond-pointed cylindrical holder 37 of conventional type carried in a bore in a mounting-block 38, the diamond 37A itself having a radiused chisel-shaped tip. The position of the block 38 can be adjusted in a vertical plane by means of a screw 39 and in a horizontal plane by means of a screw 40 and a co-operating pivoted lever 41, the end 4.2 of which is threaded and works as a nut on the screw 40. In use the position of the block is made such that the axis about which the radiused tip of the diamond is formed lies on the axis 28. The radius of the template-follower pin 23 is equal to the radius of the diamond tip multiplied by the mechanical advantage of the pantograph, which conveniently is 10 to 1.

The template-follower pin 23 is mounted for rotation about an axis perpendicular to the plane of the template, the pin and the holder 27 being connected for rocking in unison under control of a hand-wheel 43 on the pin 23. The necessary connection consists of pulleys 44 (Figures 3A and 3B) and 45 fast on their respective shafts, and steel driving tapes 46 and 47 connecting their respective pulleys to a pulley 48. The tapes are provided with tensioning springs 49; relative movement between the tapes and the pulleys over which they pass is prevented by grub screws 50 (Figures 3A and 3B).

Sector blades 51 prevent the template-follower from being accidentally manipulated in such a way that the shoulder of the dressing tool is cut by a part of the grinding wheel 14. In order to relieve the operator of most of the weight of the pantograph mechanism two tension springs 52 each have one end fixed to the prong 24 and the other end to a strap 53 which is pinned to a support 54 rigid with the support 20. Preferably the springs are so set that the template-follower pin 23 will still fall away from the template; if the spring were to overbalance the weight of the pantograph mechanism there would be a risk of the dressing tool accidentally plunging too deeply into the grinding wheel.

The improved device provides extreme rigidity of support for the dressing tool, whilst permitting it to be disposed sutficiently far from the vertically-extending portions of the device for the said portions not to foul the grinding machine while the device is in position for dressing the grinding wheel. This extreme rigidity is provided with a minimum of complication.

I claim:

1. A pantographic wheel-dressing device for attachment to a grinding machine and for forming on the grinding Wheel thereof a profile reproduced from a template, the device comprising a base for mounting on the grinding machine, a template holder fixed to the said base and for carrying a template, a link parallelogram constituted by parallel first and third arms and parallel second and fourth arms, the first arm being pivoted at one end to the base for movement about the axis of the pivot, the third arm being forked to form two prongs, the second being constituted by two independent spaced links, both individually pivoted at one of their ends to the base for movement about the said pivot axis and each being individually pivoted at its opposite end to a different one of the two prongs of the third arm and the fourth arm being pivoted to the other ends of the first and third arms and having an extension beyond one of its pivots with the first and third arms, a bearing mounted in the said extension of the fourth arm, a template follower member mounted in said bearing for rocking movement about the axis thereof, two coaxial bearings each mounted in a different one of the two prongs of the forked third arm, a dressing-tool holder extending between the two coaxial bearings and mounted therein for rocking movement about the axis thereof, and a connection supplementary to the pantograph linkage coupled to the template-follower member and the dressing-tool holder and for constraining the template-follower member and the dressing-tool holder to rock in unison.

2. A pantographic wheel-dressing device for attachment to a grinding machine and for forming on the grinding wheel thereof a profile reproduced from a template, the device comprising a base for mounting on the grinding machine, a template holder fixed to the said base and for carrying a template, a link parallelogram constituted by parallel first and third arms and parallel second and fourth arms, the first arm being pivoted at one end to the base for movement about the axis of the pivot, the third arm being forked to form two prongs, one of which extends parallel with the firstarm and the other of which extends laterally of the first arm, the second arm being constituted by two spaced independent links, both individually pivoted at one of their ends to the base for movement about said pivot axis, one of said spaced links being pivoted at its other end to the said parallel-extending prong and the other of said links being pivoted at its other end to the said laterally-extending prong, and the fourth arm being pivoted to the other ends of the first and third arms and having an extension beyond one of its pivots with the first and third arms, a bearing mounted in the said extension of the fourth arm, a template follower member mounted in said bearing for rocking movement about the axis thereof, two coaxial bearings each mounted in a ditferent one of the two prongs of the forked third arm, a dressing-tool holder extending between the two coaxial bearings and mounted therein for rocking movement about the axis thereof, and a connection supplementary to the pantograph linkage coupled to the template-follower member and the dressing-tool holder and for constraining the template-follower member and the dressing-tool holder to rock in unison.

3. A pantographic wheel dressing device as claimed in claim 1, wherein the said third arm comprises a hollow member which encloses the first arm, the two links comprising the second arm, at least the portion of the fourth arm between its pivots with the first and third arms, and the said pivots between the fourth arm and the first and third arms.

4. A pantographic wheel dressing device as claimed in claim 2, wherein the said third arm comprises a hollow unitary member which encloses the first arm, the two links comprising the second arm, at least the portion of the fourth arm between its pivots with the first and third arms and the said pivots between the fourth arm and the first and third arms.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,049 Olson Aug. 1, 1916 1,474,321 Mattia Nov. 13, 1923 2,469,844 Porter May 10, 1949 FOREIGN PATENTS 117,065 Australia June 2, 1943 643,240 Great Britain Sept. 15, 1950 

